The invention is directed to a process for the continuous polymerization of trioxane alone or together with trioxane copolymerizable compounds in the presence of a cationically active catalyst.
There are already known a large number of processes of this type which can be divided into four groups.
1. A molten starting material is polymerized in the quiescent state, that is, without the influence of stirrers or kneaders. Such processes are described, for example, in German Pat. No. 1,137,215, German AS No. 1225389, Germ AS No. 1244408 (and related Ba der in U.S. Pat. No. 3,299,003, the entire disclosure of which is hereby incorporated by reference and relied upon), German AS No. 1720300, and in German Pat. No. 2003270 (or related Ba der in U.S. Pat. No. 3,845, 160, the entire disclosure of which is hereby incorporated by reference and relied upon). In this process, the polymerizate is obtained in a form which makes necessary a subsequent comminution, e.g., in thin plates or in thick blocks.
2. A molten starting material is polymerized in self-cleaning machines provided with mixing organs whereby it is divided under gradual solidification, first being transferred into a pasty state and subsequently through the mixing organ being converted to a dry, granular polymerizate. Such processes are described, for example, in German AS No. 1161421, German AS No. 1454774, German AS No. 1495228, German AS No. 1720358, German OS No. 2543790, German OS No. 2753218, German OS No. 3018898, and German OS No. 3040049. They require the employment of very special and expensive machines.
3. A molten starting material is homogeneously mixed with the catalyst, solidified through quick cooling and polymerized in the solid condition. Such processes are described, for example, in German OS No. 2362172 and German OS No. 2362791. Likewise, they require the employment of relatively expensive machines.
4. The starting material is polymerized in or out of the vapor phase. Such a process is described in German Pat. No. 1137215. In this process, however, a large part of starting material employed passes through the reactor unchanged.
The entire disclosures of all of the above-mentioned German patents and applications are hereby incorporated by reference and relied upon.